Primase lays down a short RNA primer that gives DNA polymerase a starting 3 prime end.
DNA polymerase cannot start a chain from scratch. Primase, an RNA polymerase, makes a short RNA primer (about 10 nucleotides) that supplies the 3' OH. Later primers are replaced with DNA.
The need for primers causes the end-replication problem at telomeres.
Primase lays down a short RNA primer that gives DNA polymerase a starting 3 prime end.
Primase and RNA Primer is one of the 52 topics in Molecular Biology. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include Leading and Lagging Strands, DNA Polymerase, Okazaki Fragments.
In PCR, short DNA oligonucleotides serve as primers.
Work through the Beginner topics in Molecular Biology first, such as Central Dogma, DNA Replication, Base Pairing, then return to Primase and RNA Primer. Intermediate topics assume the Beginner vocabulary.
The closest topics to Primase and RNA Primer are Leading and Lagging Strands, DNA Polymerase, Okazaki Fragments, DNA Repair. Comparing them side by side is a good way to see how the ideas connect.
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Primase and RNA Primer. To practise the whole of Molecular Biology, use the Molecular Biology quiz.
Primase and RNA Primer: Primase lays down a short RNA primer that gives DNA polymerase a starting 3 prime end. Leading and Lagging Strands: The leading strand is made continuously, while the lagging strand is made in short Okazaki fragments. Read both side by side and note what each one explains.
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Leading and Lagging Strands and explain the difference aloud. Finally, take the Molecular Biology quiz and come back to this page for any question you miss.
The leading strand is made continuously, while the lagging strand is made in short Okazaki fragments.
🧫 Molecular BiologyThe enzyme that adds nucleotides to a growing DNA strand in the 5 prime to 3 prime direction.
🧫 Molecular BiologyShort DNA segments synthesised discontinuously on the lagging strand and joined by DNA ligase.
🧫 Molecular BiologyMechanisms such as mismatch, excision and double-strand break repair that fix errors and damage in DNA.
🧫 Molecular Biology